Maryborough was incorporated by a 1571 charter of 12 Elizabeth I. The corporation comprised a burgomaster, two bailiffs, burgesses, a serjeant-at-mace, a town clerk, a billet master, a craner or weighmaster and a pound keeper (to look after stray or impounded animals etc.). A by-law of 1738 placed the admission of freemen in the hands of the burgomaster. There was no legal limit to the number of freemen who could be admitted and, prior to 1783, after which there were no new admissions, the situation appears to have got out of hand.
The Pigotts of Dysert had had a strong local interest throughout the seventeenth century, and they carried it over into the first part of the eighteenth century. Robert Pigott (1682) sat for Maryborough from 1703 until his death in 1730, when he was succeeded by Warner Westenra (2220). In 1739 the two MPs were Warner Westenra and William Wall (2156). On 1 March 1739 Wall, who had sat for Maryborough since 1713, sold his interest in the corporation to Bartholomew William Gilbert (0848) for £500; at the same time Wall took a voluntary oath that he would take no part in the corporation as regarded parliamentary or local elections and that he would give his support to Gilbert and Westenra. He resigned his position as burgomaster and Gilbert was elected in his place. Gilbert and Westenra were then burgomaster turn and turn about until 1750, when William Henry Dawson (0597) joined them in a triumverate. Wall died in 1755 and there was a disputed election: other interests began to emerge or re-emerge. The Pigotts were joined by two late seventeenth-century families, the Parnells of Rathleague and the Poles of Ballyfin. In 1754 there was 'a strong contest for the magistracy between Bart Wm Gilbert and John Pigott Esq. Upon the poll for Mr Gilbert there was 227: for Mr Pigott 129: majority for Gilbert 98: notwithstanding Pigott by a violent mob usurped office; an information was brought in the court of King's Bench by Gilbert: judgment of ouster against Pigott but still usurped.'
This quotation is from a handlist of the voters for Maryborough328 dated 1 May 1760, indicating that there was a need to prepare for the election some six months before the king's death would dissolve parliament. Out of a total of about 400 potential voters, only 70 resided in Maryborough. The list is in three columns entitled 'Burgesses and Freemen', 'Place of Abode' and 'Observations', and attempts to identify the voters committed to some major interest and how the rest might be influenced: comments such as 'will serve whoever gives him most money', 'he will serve Mr Coote but money will prevail', and 'whoever gives his wife most money will get him' were not uncommon. Although there were quite a number of voters in Maryborough itself, there were also many much further away: for instance, there were a number in Dublin, including one who was 'somewhat under the influence of Collo Paul but is poor and will take money'; there were similar voters in Carlow, Wicklow, Ballinasloe, Kilkenny, etc. as the 1747 'Newtown Act' allowed. At the time of the 1761 election, when this poll book would have applied, the Dublin Journal reported that:
On Friday April 24 last came the election for two Burgesses to serve in Parliament for Maryborough. When opening the poll Mr Parnell and Mr Rochfort, two of the candidates upon a well grounded suspicion that several of one class of person who were not freemen or deemed so by any part of the body of the Corporate would be tendered as voters on that election, demanded from the Magistrate if he would receive them, who answered in so doubtful a manner that Messrs Parnell and Rochfort could not prepare for legal objections to them. On the third day the poll stood thus: Mr Parnell (1632) 185, Col. Coote 170, Mr Gilbert (0850) 241, Mr Rochfort 68. After which the magistrate received 22 of the class first mentioned by Mr Parnell, though he had before received 32 voices for Col. Coote and the former magistrate, totally repugnant to the Bye Laws of the said corporation; and afterwards on the scrutiny refused admitting Mr Parnell and Mr Rochfort supporting their objections to anyone of the 94 persons objected to on the poll, under pretence they were not summoned to attend the scrutiny, which was impossible to do [they] being dispersed into different parts of the kingdom; and after striking off 17 of Mr Parnell and Mr Rochfort's voters declared Mr Gilbert and Col. Coote duly elected.329
Parnell petitioned against the election, and the House of Commons decided in favour of William Gilbert and Parnell: the latter was returned in the place of Col. Coote, declared not duly elected. Large electorates not only were difficult to control but opened the way for bribery, corruption of various kinds, and the exercise of all sorts of undue influence. There were at least nine controverted elections for Maryborough during the period 1692-1800.
In the 1770s the Earl of Drogheda attempted to gain control. In 1777 it was said that 'His Lordship [Drogheda] has one Borough (Ballynakill) certain and he is now endeavouring to hold the half of Maryborough.' He did not succeed. On Thursday 30 May 1776 the poll ended for Maryborough and the voting was as follows:330 Sir John Parnell 151, Lord Jocelyn (1100) 139, Sir John Tydd (2117)125,General Walsh (2165) 106. Tydd and Hunt Walsh petitioned against the return, and the House of Commons confirmed the election of Sir John Parnell but declared John Tydd elected in place of Lord Jocelyn, who was probably Lord Drogheda's candidate.
By 1783331 Maryborough had '300 or 400 Freemen, mostly non-resident. [The town] 1,200 inhabitants. Patrons, Dean Coote and Sir John Parnell. Soil, various proprietors.' Dean Coote and Sir John Parnell continued to consolidate their hold, and in 1790 it was commented that:
This Borough, whose electors are sufficiently numerous, though by no means entitled to the praise of independence, as having been created to serve the little purposes of private party and not to support the generous interests of free election, is principally under the dominion of the Rt Hon. Sir John Parnell, Bt, but the Rev. Dean Coote possesses a powerful interest in it. An interest formerly so powerful as to be deemed to command one half of the representation, and tho' visibly declined, it still requires management and sometimes composition. In consequence of this, Charles Henry Coote (0481), Esq. the Dean's eldest son, at present represents it and probably will continue to enjoy that station at the general election  as from particular circumstances we do not apprehend that he will again think of contesting the County.332
Maryborough was disfranchised by the Act of Union and the £15,000 was equally divided between Sir John Parnell and the Rt Hon. Charles Henry Coote.